WO2019239732A1

WO2019239732A1 - Electrode for redox flow battery, and redox flow battery

Info

Publication number: WO2019239732A1
Application number: PCT/JP2019/017589
Authority: WO
Inventors: 雄大池上; 雍容董; 正幸大矢; 良潤關根
Original assignee: 住友電気工業株式会社
Priority date: 2018-06-12
Filing date: 2019-04-25
Publication date: 2019-12-19
Also published as: TW202002375A; JP7226443B2; DE112019003004T5; JPWO2019239732A1; US20210126263A1; CN112236892A

Abstract

An electrode for a redox flow battery, provided with a base and a catalyst part supported by the base. The base contains one or more elements selected from the group consisting of C, Ti, Sn, Ta, Ce, In, W, and Zn. The catalyst part contains one or more elements selected from the group consisting of Fe, Si, Mo, Ce, Mn, Cu, and W.

Description

Redox flow battery electrode and redox flow battery

The present disclosure relates to a redox flow battery electrode and a redox flow battery.

In Patent Document 1, an electrolytic solution (a positive electrode electrolyte and a negative electrode electrolyte) is supplied to a pair of electrodes (a positive electrode and a negative electrode) disposed on both sides of a diaphragm, respectively, and an electrochemical reaction (electrode) on the electrodes is performed. A redox flow battery that charges and discharges by reaction) is disclosed. For the electrode, an aggregate of carbon fibers having chemical resistance, conductivity, and liquid permeability is used.

Japanese Patent Laid-Open No. 2002-246035

An electrode for a redox flow battery according to the present disclosure is:
A substrate and a catalyst portion supported on the substrate;
The substrate contains one or more elements selected from the group consisting of C, Ti, Sn, Ta, Ce, In, W, and Zn,
The catalyst portion contains one or more elements selected from the group consisting of Fe, Si, Mo, Ce, Mn, Cu, and W.

The redox flow battery according to the present disclosure is:
A redox flow battery for supplying and discharging a positive electrode electrolyte and a negative electrode electrolyte to a battery cell comprising a positive electrode, a negative electrode, and a diaphragm interposed between the positive electrode and the negative electrode. ,
The positive electrode is a redox flow battery electrode according to the present disclosure.

FIG. 1A is a schematic diagram illustrating an electrode for a redox flow battery according to an embodiment. FIG. 1B is an enlarged view showing the redox flow battery electrode according to the embodiment. 1C is a partial cross-sectional view taken along line (C)-(C) of FIG. 1B. FIG. 2 is a cross-sectional view showing another example of a catalyst portion supported on a substrate in the redox flow battery electrode according to the embodiment. FIG. 3 is a cross-sectional view showing still another example of the support form of the catalyst portion with respect to the substrate in the redox flow battery electrode according to the embodiment. FIG. 4 is an explanatory diagram of the operating principle of the redox flow battery according to the embodiment. FIG. 5 is a schematic configuration diagram of the redox flow battery according to the embodiment. FIG. 6 is a schematic configuration diagram of a cell stack provided in the redox flow battery according to the embodiment. FIG. 7 is a cyclic voltammogram in Test Example 1. FIG. 8 is a linear sweep voltammogram in Test Example 2.

[Problems to be solved by the present disclosure]
There is a demand for further improvement of the battery performance of the redox flow battery, and further improvement of the electrode reaction is strongly desired.

Therefore, an object of the present disclosure is to provide a redox flow battery electrode that can build a redox flow battery with high battery reactivity on the electrode and low cell resistivity. Another object of the present disclosure is to provide a redox flow battery having high battery reactivity on an electrode and low cell resistivity.

[Effects of the present disclosure]
The electrode for a redox flow battery of the present disclosure can build a redox flow battery having high battery reactivity on the electrode and low cell resistivity. The redox flow battery of the present disclosure has high battery reactivity on the electrode and low cell resistivity.

[Description of Embodiment of Present Disclosure]
First, the contents of the embodiment of the present disclosure will be listed and described.

(1) An electrode for a redox flow battery according to an embodiment of the present disclosure is:
A substrate and a catalyst portion supported on the substrate;
The substrate contains one or more elements selected from the group consisting of C, Ti, Sn, Ta, Ce, In, W, and Zn,
The catalyst portion contains one or more elements selected from the group consisting of Fe, Si, Mo, Ce, Mn, Cu, and W.

The elements of the above-described element group (hereinafter referred to as element group A) as elements constituting the substrate are elements that are not easily oxidized and deteriorated. The elements of the above-described element group (hereinafter referred to as element group B) as elements constituting the catalyst portion are elements that are easily supported on the substrate composed of the elements of element group A. In addition, the element of the element group B is an element that exhibits a catalytic function effectively by being supported on a substrate composed of the element of the element group A. Furthermore, the element of the element group B is a non-noble metal element, and is an inexpensive element as compared with a noble metal element generally used as a catalyst.

The electrode for the redox flow battery of the present disclosure can suppress deterioration over time in the operation of the redox flow battery over a long period of time because the substrate contains the element of the element group A, and is excellent in durability. Moreover, the electrode for redox flow batteries of this indication can construct a redox flow battery with high battery reactivity on an electrode and small cell resistivity because a catalyst part contains the element of the said element group B. FIG. Furthermore, the redox flow battery electrode of the present disclosure can be reduced in cost compared to the case where the catalyst portion is made of a noble metal element.

(2) As an example of the redox flow battery electrode of the present disclosure,
The mass ratio of the catalyst part in the redox flow battery electrode is 0.01% or more and 70% or less.

The mass ratio of the catalyst portion in the redox flow battery electrode (hereinafter referred to as the ratio of the catalyst portion) is 0.01% or more, so that the battery reactivity on the electrode can be easily increased, and the cell resistivity is increased. Smaller redox flow batteries can be constructed. The larger the catalyst portion abundance, the easier it is to increase the cell reactivity on the electrode, but the substrate abundance is relatively reduced and the durability of the redox flow battery electrode is lowered. Therefore, when the abundance ratio of the catalyst portion is 70% or less, it is easy to obtain a redox flow battery electrode having higher battery reactivity on the electrode and excellent durability.

(3) As an example of the redox flow battery electrode of the present disclosure,
It is mentioned that the catalyst part having a part exposed from the base and a part embedded in the base is provided.

Since the catalyst portion has a portion embedded in the substrate, the catalyst portion is firmly supported on the substrate. Therefore, in the operation of the redox flow battery over a long period of time, it is easy to suppress the catalyst part from falling off the base. On the other hand, when the catalyst portion has a portion exposed from the substrate, the catalytic action can be exerted from the initial use of the redox flow battery electrode of the present disclosure.

(4) As an example of the redox flow battery electrode of the present disclosure,
The catalyst part is
A first catalyst portion having a portion exposed from the substrate;
And a second catalyst part embedded in the substrate without being exposed from the substrate.

The first catalyst portion having a portion exposed from the substrate can exert a catalytic action from the initial use of the redox flow battery electrode of the present disclosure. On the other hand, the second catalyst portion embedded in the substrate without being exposed from the substrate is exposed when the electrode is deteriorated in the operation of the redox flow battery over a long period of time, and can exhibit a catalytic action from the exposed time. Therefore, by providing both the first catalyst portion and the second catalyst portion, the catalytic action can be exhibited over a long period from the initial use of the redox flow battery electrode of the present disclosure. This is because the second catalyst portion is supported on the substrate even if the first catalyst portion falls off the substrate due to electrode deterioration in the operation of the redox flow battery over a long period of time.

(5) As an example of the redox flow battery electrode of the present disclosure,
It is possible to include a binder that covers at least a part of the catalyst portion.

By providing a binder that covers the catalyst part, the catalyst part is firmly supported on the substrate. Therefore, in the operation of the redox flow battery over a long period of time, it is easy to suppress the catalyst part from falling off the base.

(6) A redox flow battery according to an embodiment of the present disclosure is provided.
A redox flow battery for supplying and discharging a positive electrode electrolyte and a negative electrode electrolyte to a battery cell comprising a positive electrode, a negative electrode, and a diaphragm interposed between the positive electrode and the negative electrode. ,
The positive electrode is the redox flow battery electrode according to any one of (1) to (5) above.

The redox flow battery of the present disclosure uses the redox flow battery electrode of the present disclosure as the positive electrode, and therefore has high battery reactivity on the electrode and low cell resistivity. In a redox flow battery, the positive electrode is oxidatively deteriorated due to side reactions accompanying charge and discharge, and the cell resistivity is likely to increase. Therefore, the cell resistivity can be effectively reduced by using the redox flow battery electrode of the present disclosure for the positive electrode.

(7) As an example of the redox flow battery,
The negative electrode may be a redox flow battery electrode according to any one of (1) to (5) above.

The cell resistivity can be further reduced by using the redox flow battery electrode of the present disclosure also for the negative electrode.

(8) As an example of the redox flow battery,
The positive electrode electrolyte contains manganese ions as a positive electrode active material,
The said negative electrode electrolyte solution contains a titanium ion as a negative electrode active material.

In the case of a manganese-titanium-based electrolyte containing manganese ions as the positive electrode active material and titanium ions as the negative electrode active material, the positive electrode is likely to be oxidized and deteriorated. Therefore, in the case of a manganese-titanium-based electrolytic solution, the cell resistivity can be effectively reduced by using the redox flow battery electrode of the present disclosure as the positive electrode.

(9) As an example of the redox flow battery containing manganese ions as the positive electrode active material and titanium ions as the negative electrode active material,
The concentration of the manganese ions and the concentration of the titanium ions may be 0.3 mol / L or more and 5 mol / L or less, respectively.

Obtaining a manganese-titanium redox flow battery having a high energy density and containing a sufficient amount of a metal element that undergoes a valence change reaction when the manganese ion concentration and the titanium ion concentration are each 0.3 mol / L or more. Can do. On the other hand, when the concentration of manganese ions and the concentration of titanium ions are each 5 mol / L or less, even when the electrolytic solution is an aqueous acid solution, it can be dissolved well, and the productivity of the electrolytic solution is excellent.

[Details of Embodiment of the Present Disclosure]
Details of the redox flow battery electrode and the redox flow battery according to the embodiment of the present disclosure will be described below with reference to the drawings. The same code | symbol in a figure shows the same name thing.

≪Redox flow battery electrode≫
With reference to FIG. 1 to FIG. 3, a redox flow battery electrode 10 (hereinafter, simply referred to as an “electrode”) according to an embodiment will be described. The electrode 10 according to the embodiment is used as a constituent element of the redox flow battery 1 (FIG. 4), and is a reaction field where an active material contained in an electrolytic solution performs a battery reaction. FIG. 1A is an overall view of the electrode 10. FIG. 1B is a partially enlarged view of the electrode 10. As shown in FIG. 1B, the electrode 10 is composed of a fiber assembly mainly composed of a plurality of fibers that are intertwined with each other. In FIG. 1B, the some fiber which comprises the electrode 10 is shown typically. FIG. 1C is a cross-sectional view of each fiber (base 110) constituting the electrode 10 cut along a plane parallel to the longitudinal direction of the fiber. As shown in FIG. 1C, the electrode 10 includes a base 110 and a catalyst unit 111 supported on the base 110. One feature of the electrode 10 according to the embodiment is that each of the elements constituting the substrate 110 and the catalyst part 111 contains a specific element.

[Substrate]
The substrate 110 is selected from the group consisting of carbon (C), titanium (Ti), tin (Sn), tantalum (Ta), cerium (Ce), indium (In), tungsten (W), and zinc (Zn). Containing one or more elements. The substrate 110 may be a material made of a single element or a material made of an alloy or compound containing the above element. The substrate 110 may contain an element other than the elements listed above. The base 110 constitutes the base of the electrode 10. As for the base | substrate 110, it is mentioned that the ratio which occupies for the electrode 10 is 30 to 99 mass%. The base 110 has a different proportion of fibers in the fiber assembly (electrode 10) depending on its structure (fiber combination form). Examples of the combination form of the fibers of the fiber assembly include nonwoven fabric, woven fabric, and paper.

As for the average diameter of the cross section of the fibers constituting the substrate 110, the equivalent circle diameter is 3 μm or more and 100 μm or less. The cross section of the fiber mentioned here is a cross section cut along a plane parallel to the direction orthogonal to the longitudinal direction of the fiber. When the equivalent circle diameter of the fiber is 3 μm or more, the strength of the fiber assembly can be ensured. On the other hand, when the equivalent circle diameter of the fiber is 100 μm or less, the surface area of the fiber per unit weight can be increased, and a sufficient battery reaction can be performed. The equivalent circle diameter of the fiber is further 5 μm or more and 50 μm or less, particularly 7 μm or more and 20 μm or less. The equivalent circle diameter referred to here is the diameter of a perfect circle having the cross-sectional area of the fiber. The average diameter of the cross section of the fiber constituting the substrate 110 is obtained by cutting the electrode 10 to expose the cross section of the fiber, and averaging the results measured under a microscope for five or more fields and three or more fibers per field. Is required.

It can be mentioned that the porosity of the fiber assembly by the substrate 110 is more than 40% by volume and less than 98% by volume. When the porosity of the fiber assembly is more than 40% by volume, the flowability of the electrolytic solution can be improved. On the other hand, when the porosity of the fiber assembly is less than 98% by volume, the density of the fiber assembly can be increased, the conductivity can be improved, and a sufficient battery reaction can be performed. It can be mentioned that the porosity of the fiber aggregate by the substrate 110 is 60% by volume to 95% by volume, particularly 70% by volume to 93% by volume.

(Catalyst part)
The catalyst unit 111 is one or more selected from the group consisting of iron (Fe), silicon (Si), molybdenum (Mo), cerium (Ce), manganese (Mn), copper (Cu), and tungsten (W). Contains the elements. The catalyst part 111 is preferably made of a non-noble metal element containing the elements listed above. When the catalyst unit 111 contains one element selected from the element group listed above, the catalyst part 111 contains the element simple substance, the oxide of the element, or both the element simple substance and the oxide of the same element. Is mentioned. When the catalyst unit 111 contains a plurality of types of elements selected from the element group listed above, a plurality of types of elements, a plurality of types of oxides of each element, a compound containing a plurality of types of each element, It may be contained in a solid solution containing a plurality of types, or a combination thereof. For example, when a plurality of kinds of elements selected from the element group listed above are X and Y, two kinds of element simple substance: X + Y, two kinds of oxides of each element: X _n O _m + Y _p O _q , A compound containing two kinds of each element (composite oxide): (X _s , Y _t ) O and the like. In particular, the catalyst part 111 is often contained in the form of an oxide of an element selected from the element group listed above (each element in the case where a plurality of kinds are included). Although the catalyst part 111 may contain elements other than the element enumerated above, it is preferable that the element is also a non-noble metal element. The catalyst unit 111 is supported on the substrate 110 and improves battery reactivity on the electrode 10.

The base 110 and the catalyst part 111 may contain the same element. In this case, the base 110 is made of a single element, and the catalyst part 111 is made of a compound of the element. An oxide is mentioned as a compound. For example, when both the base 110 and the catalyst part 111 contain W, a form in which the catalyst part 111 made of W oxide is supported on the base 110 made of W alone is exemplified. Further, when both the base 110 and the catalyst part 111 contain Ce, a form in which the catalyst part 111 made of Ce oxide is supported on the base 110 made of Ce alone can be cited. Even when the base 110 and the catalyst part 111 contain the same element, it can be determined by observing the crystal structure with a transmission electron microscope (TEM). . This is because elemental elements and elemental compounds have different crystal structures.

The catalyst unit 111 is supported on the base 110. The term “supporting” as used herein means that the catalyst unit 111 is fixed in a state of being electrically connected to the base 110. As a form in which the catalyst part 111 is fixed to the base 110, there are a form in which the catalyst part 111 is directly fixed to the base 110 and a form in which the catalyst part 111 is indirectly fixed to the base 110. As a form in which the catalyst unit 111 is directly fixed to the base 110, as shown in FIG. 1C, the catalyst unit 111 is attached to the surface of the base 110. Further, as a form in which the catalyst unit 111 is directly fixed to the base 110, at least a part of the catalyst unit 111 is embedded in the base 110 as shown in FIG. Specifically, a form in which the catalyst part 111 has a part exposed from the base 110 and a part embedded in the base 110 can be mentioned. By having the catalyst portion 111 exposed from the base 110, the catalytic action can be exerted from the beginning of use of the electrode 10. On the other hand, the catalyst portion 111 has a portion embedded in the base 110, so that the catalyst portion 111 is firmly supported on the base 110, and the catalyst portion 111 becomes a base in the operation of the redox flow battery 1 (FIG. 4) for a long time. It is easy to suppress dropping from 110. In addition, as shown in FIG. 2, the catalyst unit 111 may be embedded in the base 110 without being exposed from the base 110. When the catalyst part 111 is completely embedded in the base 110, the catalyst part 111 is exposed when the electrode 10 deteriorates with time. The exposed catalyst portion 111 exhibits a catalytic action. The catalyst portion 111 (FIG. 1C) attached to the surface of the substrate 110, the catalyst portion 111 (FIG. 2) partially embedded in the substrate 110, and the catalyst portion 111 completely embedded in the substrate 110. (FIG. 2) may be mixed. The catalyst portion 111 that is completely embedded in the substrate 110 cannot exert a catalytic action in the initial use of the electrode 10. Therefore, the catalyst part 111 having a portion exposed from the base 110 is necessarily included.

The electrode 10 can be provided with a binder 112 that covers at least a part of the catalyst part 111 as shown in FIG. It is mentioned that the binder 112 is provided so as to cover the both 110 and 111 from the base 110 to the catalyst part 111. As a form in which the catalyst unit 111 is indirectly fixed to the substrate 110, the catalyst unit 111 is not attached to the substrate 110, and the catalyst unit 111 is fixed in contact with the substrate 110 by the binder 112. When the binder 112 is provided, the base 110 and the catalyst part 111 may not be in contact with each other, and the binder 112 may be interposed between the base 110 and the catalyst part 111. When the base 110 and the catalyst part 111 are not in contact with each other, the catalyst part 111 and the base 110 cannot be electrically connected. Therefore, when the binder 112 is provided, the catalyst part 111 in a state of being in direct contact with the substrate 110 is necessarily included. The catalyst unit 111 is directly fixed to the base 110, and may be further fixed by the binder 112. That is, the catalyst part 111 attached to the base 110 and the catalyst part 111 having a portion embedded in the base 110 may be included, and the binder 112 may be further provided. In any case, the catalyst unit 111 is firmly supported on the base 110 by including the binder 112. The catalyst portion 111 that is completely covered with the binder 112 cannot exert a catalytic action in the initial use of the electrode 10. Therefore, the catalyst part 111 having a part exposed from the binder 112 is necessarily included.

The binder 112 contains one or more elements selected from the group consisting of carbon (C), aluminum (Al), and phosphorus (P). It can be mentioned that the mass ratio of the binder 112 in the electrode 10 is 1% or more and 50% or less, and further 20% or more and 40% or less. The said mass ratio is a mass ratio of the total content of the element which comprises the binder 112 when the total content of the base | substrate 110, the catalyst part 111, and the binder 112 is 100 mass%. The mass ratio of the binder 112 is obtained by thermogravimetry (TG).

The catalyst unit 111 is typically a solid. As a solid substance, a granular material, a needle-shaped body, a rectangular parallelepiped, a short fiber, a long fiber, etc. are mentioned. Typically, as shown in FIG. 1C, the catalyst part 111 is present almost uniformly dispersed over the entire region of the substrate 110. The catalyst unit 111 may include a portion that is in direct contact with and in contact with the substrate 110. This is because the catalyst part 111 containing the above-mentioned specific element is easily supported on the substrate 110 containing the above-mentioned specific element, thereby easily exerting a catalytic effect effectively. The catalyst part 111 containing the specific element is easily supported directly on the substrate 110 containing the specific element.

The mass ratio of the catalyst part 111 occupying the electrode 10 (existence ratio of the catalyst part 111) is 0.01% or more and 70% or less. The abundance ratio of the catalyst part 111 is a mass ratio of the total content of elements constituting the catalyst part 111 when the electrode 10 is 100 mass%. For example, when the electrode 10 includes the base 110 and the catalyst part 111, the total content of the base 110 and the catalyst part 111 is 100% by mass. Moreover, when the electrode 10 is comprised by the base | substrate 110, the catalyst part 111, and the binder 112 (FIG. 3), the sum total content of the base | substrate 110, the catalyst part 111, and the binder 112 shall be 100 mass%. The presence ratio of the catalyst part 111 is 0.01% or more, so that the battery reactivity on the electrode 10 can be easily improved and the redox flow battery 1 having a smaller cell resistivity can be constructed. The larger the abundance ratio of the catalyst part 111 is, the easier it is to improve the cell reactivity on the electrode 10, but the abundance ratio of the substrate 110 is relatively reduced, and the durability of the electrode 10 is lowered. Therefore, when the abundance ratio of the catalyst portion 111 is 70% or less, it is easy to obtain the electrode 10 having higher battery reactivity on the electrode 10 and excellent durability. The abundance ratio of the catalyst portion 111 is further 0.1% to 70%, 1% to 70%, particularly 10% to 50%, 10% to 30%. The abundance ratio of the catalyst part 111 is obtained by TG.

[Weight per unit]
Electrode 10 is mentioned that the basis weight (weight per unit area) of 50 g / ^{m 2} or more 10000 g / ^{m 2} or less. When the basis weight of the electrode 10 is 50 g / m ² or more, a sufficient battery reaction can be performed. On the other hand, when the basis weight is 10000 g / m ² or less, it is possible to suppress the voids from becoming excessively small, and to easily suppress an increase in the flow resistance of the electrolytic solution. The basis weight of the electrode 10 is further 100 g / m ² or more and 2000 g / m ² or less, particularly 200 g / m ² or more and 700 g / m ² or less.

[Thickness]
The electrode 10 preferably has a thickness of 0.1 mm or more and 5 mm or less when no external force is applied. When the thickness of the electrode 10 is 0.1 mm or more, a battery reaction field for performing a battery reaction with the electrolytic solution can be increased. On the other hand, when the thickness of the electrode 10 is 5 mm or less, the redox flow battery 1 using the electrode 10 can be made thin. The said thickness of the electrode 10 is further 0.2 mm or more and 2.5 mm or less, Especially 0.3 mm or more and 1.5 mm or less are mentioned.

≪Method for manufacturing electrode for redox flow battery≫
The electrode 10 described above is obtained by preparing a base 110 and a coating solution containing the constituent elements of the catalyst unit 111, applying the coating solution to the surface of the base 110, and performing a heat treatment.

As the substrate 110, a fiber assembly in which fibers containing one or more elements selected from the group consisting of C, Ti, Sn, Ta, Ce, In, W, and Zn are intertwined with each other is prepared. What is necessary is just to select suitably the magnitude | size and shape of this fiber assembly so that it may become the magnitude | size and shape of a desired electrode 10. FIG. The prepared fiber aggregate may be subjected to blasting, etching treatment or the like, and the one subjected to surface area expansion and surface roughening is used. After blasting or etching, the surface is selectively etched to clean and activate. As acids used for acid cleaning in cleaning, there are typically sulfuric acid, hydrochloric acid, hydrofluoric acid, etc., and activation can be performed by immersing the fiber assembly in these liquids and dissolving a part of the surface. it can.

A coating solution containing a raw material for the element constituting the catalyst unit 111 and a solvent is prepared. Examples of raw materials for elements constituting the catalyst unit 111 include metal alkoxides, chlorides, acetates, and organometallic compounds. Specific examples include ammonium tungstate pentahydrate, tungsten chloride, sodium tungstate hydrate, and the like. In addition, iron chloride, hexaammonium hexamolybdate tetrahydrate, cerium carbonate, manganese sulfate, copper sulfate and the like can be mentioned. As the solvent, water or an organic solvent can be used. Examples of the organic solvent include methanol, ethanol, propyl alcohol, isopropanol, butanol, pentanol, hexanol and the like. Examples of the solvent include 70% by mass to 95% by mass with respect to the entire coating solution. The coating liquid can contain acetylacetone as a stabilizer. It is mentioned that a stabilizer contains 1 to 10 mass% with respect to the whole coating liquid. By stirring the contents containing these raw materials, solvent, and further stabilizer in a nitrogen atmosphere for about 1 hour to 5 hours, a coating solution containing the desired constituent elements of the catalyst portion 111 can be obtained.

Apply the obtained coating solution to the surface of the obtained fiber assembly. Examples of the coating method include a brush coating method, a spray method, a dipping method, a flow coating method, and a roll coating method. After the coating solution is applied to the fiber assembly, it is dried. Thereafter, the fiber assembly to which the coating solution has been applied is subjected to a heat treatment at 300 ° C. to 700 ° C. for 10 minutes to 5 hours in an oxygen-containing atmosphere. The atmosphere containing oxygen includes an oxidizing atmosphere and an atmosphere in which the oxidation state is adjusted in a gas containing a reducing gas, and examples thereof include air. By setting the heat treatment temperature to 300 ° C. or more and the heat treatment time to 10 minutes or more, the catalyst part 111 can be adhered while being dispersed almost uniformly over the entire region of the substrate 110. On the other hand, by setting the heat treatment temperature to 700 ° C. or less and the heat treatment time to 5 hours or less, it is possible to suppress the existence ratio of the catalyst part 111 with respect to the base 110 from becoming too large. The heat treatment temperature may be 400 ° C. or more and 600 ° C. or less, particularly 450 ° C. or more and 550 ° C. or less. Further, the heat treatment time is further set to 15 minutes to 2 hours, particularly 30 minutes to 1 hour.

By the heat treatment, the constituent elements of the catalyst unit 111 penetrate into the fiber assembly by thermal diffusion, and the catalyst unit 111 is dispersed and adhered to the outer peripheral surface of each fiber (base 110) constituting the fiber assembly. In the electrode 10 obtained by applying a heat treatment after applying the coating solution on the surface of the substrate 110, the catalyst portion 111 is mainly attached to the surface of the substrate 110. Further, in the electrode 10 obtained by performing the heat treatment, a part of the catalyst part 111 may be embedded in the base 110.

In addition, the catalyst unit 111 can be supported on the substrate 110 using physical vapor deposition (PVD) or chemical vapor deposition (CVD). Examples of the PVD method include a sputtering method. Specifically, a single element constituting the catalyst unit 111 or an oxide of the element is attached to the prepared substrate 110 by a PVD method or a CVD method. When the element simple substance which comprises the catalyst part 111 adheres to the base | substrate 110, heat processing is mentioned after adhesion. By this heat treatment, the elements attached to the substrate 110 are oxidized. The heat treatment condition may be 300 ° C. or more and 700 ° C. or less × 15 minutes or more and 2 hours or less in an oxygen-containing atmosphere, for example, air. In the electrode 10 obtained by using the PVD method or the CVD method, the catalyst part 111 is mainly in a state where a part of the catalyst part 111 is embedded in the base 110.

When the catalyst unit 111 is supported on the substrate 110 using the PVD method or the CVD method, the catalyst unit 111 can be completely embedded in the substrate 110 by melting the surface of the prepared substrate 110.

The electrode 10 including the binder 112 is obtained by applying a heat treatment by applying a binder liquid containing the constituent elements of the catalyst unit 111 to the surface of the substrate 110. The binder liquid contains a raw material for the element constituting the catalyst part 111, a raw material for the element constituting the binder 112, and a solvent. Examples of the raw material for the element constituting the catalyst part 111 and the raw material for the element constituting the binder 112 include the use of a single element. As the solvent, water or an organic solvent can be used. Examples of the method for applying the binder liquid to the substrate 110 include a brush coating method, a spraying method, a dipping method, a flow coating method, and a roll coating method. After the binder liquid is applied to the substrate 110, it is dried. Thereafter, the substrate 110 coated with the binder liquid is subjected to heat treatment in an atmosphere containing oxygen, for example, in air, for example, at 300 ° C. to 700 ° C. × 15 minutes to 2 hours.

≪Redox flow battery≫
A redox flow battery 1 (RF battery) according to the embodiment will be described with reference to FIGS. As shown in FIG. 4, the RF battery 1 is typically connected to a power generation unit and a load such as a power system or a consumer via an AC / DC converter, a transformer facility, and the like. The RF battery 1 performs charging using the power generation unit as a power supply source, and performs discharging using the load as a power consumption target. Examples of the power generation unit include a solar power generator, a wind power generator, and other general power plants.

As shown in FIG. 4, the RF battery 1 includes a battery cell 100 and a circulation mechanism (a positive electrode circulation mechanism 100 </ b> P and a negative electrode circulation mechanism 100 </ b> N) that circulates and supplies an electrolytic solution to the battery cell 100. The battery cell 100 is separated into a positive electrode cell 12 and a negative electrode cell 13 by a diaphragm 11. The positive electrode cell 12 includes a positive electrode 14 to which a positive electrode electrolyte is supplied, and the negative electrode cell 13 includes a negative electrode 15 to which a negative electrode electrolyte is supplied. One of the features of the RF battery 1 according to the embodiment is that the positive electrode 14 includes the electrode 10 according to the above-described embodiment. In this example, the negative electrode 15 is also composed of the electrode 10 according to the above-described embodiment.

The battery cell 100 is configured to be sandwiched between a set of cell frames 16 and 16 as shown in FIG. The cell frame 16 includes a bipolar plate 161 on which the positive electrode 14 and the negative electrode 15 are disposed on the front and back surfaces, and a frame 162 that surrounds the periphery of the bipolar plate 161.

The diaphragm 11 is a separation member that separates the positive electrode 14 and the negative electrode 15 and transmits predetermined ions. The bipolar plate 161 is made of a conductive member that allows current to flow but does not allow electrolyte to pass through. The bipolar plate 161 is disposed so that the positive electrode 14 is in contact with one surface (front surface) side, and the negative electrode 15 is disposed on the opposite surface (back surface) side of the bipolar plate 161. The frame body 162 forms a region to be the battery cell 100 inside. Specifically, the thickness of the frame body 162 is larger than the thickness of the bipolar plate 161. The frame body 162 surrounds the periphery of the bipolar plate 161, thereby forming a step between the front surface (back surface) of the bipolar plate 161 and the front surface (back surface) of the frame body 162. A space in which the positive electrode 14 (negative electrode 15) is disposed is formed inside the step.

The positive electrode circulation mechanism 100 </ b> P that circulates and supplies the positive electrode electrolyte to the positive electrode cell 12 includes a positive electrode electrolyte tank 18,

conduits

20 and 22, and a pump 24. The positive electrode electrolyte tank 18 stores a positive electrode electrolyte. The

conduits

20 and 22 connect between the positive electrode electrolyte tank 18 and the positive electrode cell 12. The pump 24 is provided in the conduit 20 on the upstream side (supply side). The negative electrode circulation mechanism 100 </ b> N that circulates and supplies the negative electrode electrolyte to the negative electrode cell 13 includes a negative electrode electrolyte tank 19,

conduits

21 and 23, and a pump 25. The negative electrode electrolyte tank 19 stores a negative electrode electrolyte. The

conduits

21 and 23 connect between the negative electrode electrolyte tank 19 and the negative electrode cell 13. The pump 25 is provided in the conduit 21 on the upstream side (supply side).

The positive electrolyte solution is supplied from the positive electrode electrolyte tank 18 to the positive electrode 14 via the upstream conduit 20 and returned from the positive electrode 14 to the positive electrolyte tank 18 via the downstream (discharge side) conduit 22. . Further, the negative electrode electrolyte is supplied from the negative electrode electrolyte tank 19 to the negative electrode 15 through the upstream conduit 21, and from the negative electrode 15 to the negative electrolyte tank 19 through the downstream (discharge side) conduit 23. Returned. 4 and 5, manganese (Mn) ions and titanium (Ti) ions shown in the positive electrode electrolyte tank 18 and the negative electrode electrolyte tank 19 are ions contained as active materials in the positive electrode electrolyte and the negative electrode electrolyte. An example of a species is shown. In FIG. 4, a solid line arrow means charging, and a broken line arrow means discharging. By circulating the positive electrode electrolyte and the negative electrode electrolyte, the positive electrode electrolyte is circulated and supplied to the positive electrode 14 and the negative electrode electrolyte is circulated and supplied to the negative electrode 15 while the active material ions in the electrolyte of each electrode are circulated. Charge / discharge is performed with the valence change reaction.

The positive electrode electrolyte includes, for example, at least one selected from manganese ions, vanadium ions, iron ions, polyacids, quinone derivatives, and amines as a positive electrode active material. In addition, the negative electrode electrolyte includes one or more selected from titanium ions, vanadium ions, chromium ions, polyacids, quinone derivatives, and amines as the negative electrode active material. The concentration of the positive electrode active material and the concentration of the negative electrode active material can be appropriately selected. For example, at least one of the concentration of the positive electrode active material and the concentration of the negative electrode active material may be 0.3 mol / L or more and 5 mol / L or less. If the said density | concentration is 0.3 mol / L or more, it can have sufficient energy density (for example, about 10 kWh / m < ³ >) as a large capacity storage battery. Since the energy density is increased as the concentration is higher, the concentration can be set to 0.5 mol / L or more, further 1.0 mol / L or more, 1.2 mol / L or more, or 1.5 mol / L or more. Considering the solubility in a solvent, the concentration is 5 mol / L or less, more preferably 2 mol / L or less, and the electrolyte solution is excellent in productivity. As the electrolytic solution, in addition to the active material, an aqueous solution containing one or more acids or acid salts selected from sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid can be used.

The RF battery 1 is typically used in a form called a cell stack 200 in which a plurality of battery cells 100 are stacked. As shown in FIG. 6, the cell stack 200 includes a laminated body in which a certain cell frame 16, a positive electrode 14, a diaphragm 11, a negative electrode 15, and another cell frame 16 are repeatedly laminated, and a pair of end plates that sandwich the laminated body. 210, 220, a connecting member 230 such as a long bolt connecting the

end plates

210, 220, and a fastening member such as a nut. When the

end plates

210 and 220 are tightened by the fastening member, the stacked body is maintained in the stacked state by the tightening force in the stacking direction. The cell stack 200 is used in a form in which a predetermined number of battery cells 100 are sub-stacks 200S and a plurality of sub-stacks 200S are stacked. Supply and discharge plates (not shown) are disposed in place of the bipolar plates 161 on the cell frames 16 positioned at both ends of the sub stack 200S and the battery stack 100 in the cell stack 200 in the stacking direction.

The supply of the electrolyte solution of each electrode to the positive electrode 14 and the negative electrode 15 is performed by supplying a liquid supply manifold 163 formed on one piece (a liquid supply side piece, the lower side in FIG. 6) of the frame body 162 in the cell frame 16. 164, liquid supply slits 163s and 164s, and a liquid supply rectification unit (not shown). The electrolyte solution of each electrode from the positive electrode 14 and the negative electrode 15 is discharged from a drainage rectification unit (not shown) formed on the other piece (drainage side piece, upper side in FIG. 6) facing the frame 162. ), Drainage slits 165s and 166s, and

drainage manifolds

165 and 166. The positive electrode electrolyte is supplied from the liquid supply manifold 163 to the positive electrode 14 through a liquid supply slit 163s formed on one side (the front side of the paper) of the frame 162. The positive electrode electrolyte flows from the lower side to the upper side of the positive electrode 14 as indicated by the arrow in the upper diagram of FIG. 6, and passes through the drain slit 165 s formed on one side (the front side of the paper) of the frame 162. It is discharged to the drainage manifold 165. The supply and discharge of the negative electrode electrolyte are the same as those of the positive electrode electrolyte except that the negative electrode electrolyte is supplied and discharged on the opposite side of the frame 162 (the back side of the paper). An annular seal member 167 (FIGS. 5 and 6) such as an O-ring or a flat packing is disposed between the frame bodies 162 in order to suppress leakage of the electrolytic solution from the battery cell 100. A seal groove (not shown) for arranging the annular seal member 167 is formed in the frame body 162 in the circumferential direction.

As the basic configuration of the RF battery 1 described above, a known configuration can be used as appropriate.

〔effect〕
The electrode 10 for a redox flow battery according to the embodiment includes one or more kinds selected from an element group B consisting of specific elements on a base 110 containing one or more elements selected from an element group A consisting of specific elements. A catalyst part 111 containing an element is supported. With this configuration, the electrode 10 can construct the RF battery 1 that is excellent in reactivity with the electrolytic solution and has a low cell resistivity. The element group A is composed of C, Ti, Sn, Ta, Ce, In, W, and Zn. The element group B includes Fe, Si, Mo, Ce, Mn, Cu, and W. The elements of the element group B are easily supported on the substrate 110 composed of the elements of the element group A, and are effectively supported on the substrate 110 composed of the elements of the element group A, thereby effectively improving the catalytic function. It is because it demonstrates. Particularly, in the electrode 10, the mass ratio of the catalyst portion 111 occupying the electrode 10 is 0.01% or more, so that the battery reactivity on the electrode 10 can be easily increased, and the RF battery 1 having a smaller cell resistivity. Can be built.

As a form of the electrode 10, a part of the catalyst part 111 is embedded in the base 110, or a part of the catalyst part 111 is covered with the binder 112, so that the catalyst part 111 is easily supported firmly on the base 110. Since the catalyst unit 111 is firmly supported on the base 110, it is easy to suppress the catalyst unit 111 from dropping from the base 110 in the operation of the RF battery 1 over a long period of time. In addition to the first catalyst part 111 having a portion exposed from the base 110, the second catalyst part 111 that is not exposed from the base 110 and is embedded in the base 110 is provided. Catalytic action can be exerted. By exhibiting the catalytic action over a long period of time, the reactivity between the electrode 10 and the electrolyte can be favorably maintained over a long period of time. This is because the second catalyst unit 111 is exposed when the electrode 10 is deteriorated in the operation of the RF battery 1 over a long period of time, and can exhibit a catalytic action from the exposed time. That is, even if the first catalyst unit 111 falls off the base 110 due to the deterioration of the electrode 10 in the operation of the RF battery 1 over a long period of time, the second catalyst unit 111 is supported on the base 110.

The electrode 10 is less susceptible to oxidative degradation because the base 110 contains the element of the element group A, can suppress deterioration over time in the operation of the RF battery 1 over a long period of time, and is excellent in durability. Furthermore, the electrode 10 can reduce cost compared with the case where only the noble metal element generally used as a catalyst is used because the catalyst part 111 contains the element of the element group B.

The RF battery 1 according to the embodiment uses the redox flow battery electrode 10 according to the embodiment as the positive electrode 14, so that the battery reactivity on the electrode is high and the cell resistivity is low. In the RF battery 1, the positive electrode 14 is oxidized and deteriorated due to a side reaction accompanying charging and discharging, and the cell resistivity is likely to increase. Therefore, the cell resistivity can be effectively reduced by using the electrode 10 as the positive electrode 14. In particular, in the case where the electrolytic solution of the RF battery 1 is a manganese-titanium-based electrolytic solution containing manganese ions as the positive electrode active material and titanium ions as the negative electrode active material, the positive electrode is likely to be oxidized and deteriorated. Therefore, the cell resistivity can be effectively reduced by using the electrode 10 as the positive electrode 14.

The RF battery 1 is a large-capacity storage battery for the purpose of stabilizing fluctuations in power generation output, storing power when surplus generated power, leveling load, etc., with respect to natural power generation such as solar power generation and wind power generation. Available to: Further, the RF battery 1 can be suitably used as a large-capacity storage battery that is installed in a general power plant and is intended for measures against instantaneous voltage drop, power failure, and load leveling.

[Test Example 1]
An electrode including a catalyst part containing a non-noble metal element was produced, and the battery reactivity on the electrode and the cell resistivity of an RF battery using the electrode were examined.

[Sample preparation]
・ Sample No. 1-1
An electrode including a substrate and a catalyst portion supported on the substrate was produced.
Using a carbon paper made of a plurality of carbon fibers as a substrate, a fiber assembly having a size of 3.3 mm × 2.7 mm and a thickness of 0.45 mm was produced. In this fiber assembly, the fiber diameter of each carbon fiber was 10 μm in terms of equivalent circle diameter, and the porosity was 85% by volume.
As a coating solution containing the constituent elements of the catalyst unit was prepared an aqueous solution containing ammonium tungstate pentahydrate _{_{_{_{((NH 4) 10 W 12}}}} O 41 · 5H 2 O). The solvent (water) was 1% by mass with respect to the entire coating solution.
The said base | substrate was immersed in the said coating liquid, and the said coating liquid was made to adhere to the outer peripheral surface of a base | substrate (each carbon fiber). After drying the substrate to which the coating solution adhered, heat treatment was performed at 480 ° C. for 1 hour.

The obtained electrode (Sample No. 1-1) was examined for a cross section using a scanning electron microscope and an analyzer (SEM-EDX) using energy dispersive X-ray spectroscopy. As a result, sample no. In the electrode 1-1, it was confirmed that the catalyst portion was present in a substantially uniformly dispersed manner on the outer peripheral surface of the substrate (each carbon fiber). Moreover, it was confirmed that the catalyst part attached to the outer peripheral surface of the substrate (each carbon fiber) and the catalyst part partially embedded in the substrate (each carbon fiber) were mixed. The crystal structure was measured by an X-ray diffraction method (XRD), and the element composition was measured by an X-ray microanalyzer (EPMA) to examine the existence state of the catalyst part. As a result, it was found that the catalyst portion was present in the form of tungsten oxide (WO ₃ ). The mass proportion of the catalyst portion in the electrode was 20%.

・ Sample No. 1-11
As an electrode, Sample No. A substrate similar to the substrate of 1-1 was produced. Sample No. The electrode 1-11 is composed only of a substrate and does not include a catalyst portion.

[Battery reactivity]
In the above sample No. 1-1 and Sample No. Each of the electrodes 1-11 was immersed in a previously charged electrolyte solution, and potential scanning was performed. This electrolytic solution contains manganese ions having a concentration of 1.0 mol / L. The potential scan was repeated in the range of 0.5 V to 1.6 V at 3 mV / s until a steady cyclic voltammogram was obtained using a silver / silver chloride electrode as a reference electrode. The result is shown in FIG. In FIG. 7, the horizontal axis represents the applied potential, and the vertical axis represents the response current value. In the cyclic voltammogram curve in FIG. 7, the upper curve indicates an oxidation wave, and the lower curve indicates a reduction wave. In FIG. 1-1 is indicated by a solid line, and sample No. 1-11 is indicated by a broken line.

In the cyclic voltammogram shown in FIG. 1-1 and sample no. When the 1-11 oxidation waves or reduction waves are compared, the larger the absolute value of the current value, the greater the battery reactivity on the electrode. Sample No. 1-1 and sample no. When comparing the oxidation waves of 1-11, the sample No. In 1-1, the peak of the current value was observed around the potential of 1.40 V. In 1-11, a peak of the current value is seen around the potential of 1.46V. Sample No. 1-1 is Sample No. It can be seen that the absolute value of the current value is larger than that of 1-11. Sample No. 1-1 and sample no. When the reduction waves of 1-11 are compared, In 1-1, the peak of the current value was observed around the potential of 1.26 V. In 1-11, a peak of the current value is seen around the potential of 1.17V. Sample No. 1-1 is Sample No. It can be seen that the absolute value of the current value is larger than that of 1-11. Sample No. The reason why the absolute value of the current value 1-1 is large is that the catalyst part made of tungsten oxide is supported on the base made of carbon fiber, so that the catalytic function of the catalyst part was effectively exhibited. Conceivable. The battery reactivity on the electrode can be improved by effectively exerting the catalytic function of the catalyst portion.

In the cyclic voltammogram shown in FIG. 1-1 and sample no. When the 1-11 oxidation wave potential and the reduction wave potential are compared, the smaller the potential difference near the peak of the current value, the greater the battery reactivity on the electrode. As a result, sample no. 1-1 is Sample No. It can be seen that the potential difference is small compared to 1-11. Sample No. The reason why the potential difference of 1-1 is small is considered that the catalytic function of the catalyst part was effectively exhibited because the catalyst part made of tungsten oxide was supported on the base made of carbon fiber. The battery reactivity on the electrode can be improved by effectively exerting the catalytic function of the catalyst portion.

[Cell resistivity]
An RF battery having a single cell structure was fabricated using a positive electrode, a negative electrode, and a diaphragm. In the positive electrode, the above-mentioned sample No. 1-1 and Sample No. 1-11 electrodes were used. Sample no. The same electrode (carbon fiber aggregate without a catalyst part) as in 1-11 was used. As the electrolytic solution, a manganese-titanium-based electrolytic solution containing manganese ions as an active material and a titanium ion as an active material was used as a negative electrode electrolytic solution. Since each sample was an RF battery having a single cell structure, the internal resistance of the RF battery is expressed as cell resistivity. About each sample, the battery cell was charged / discharged with the constant current whose current density is 256 mA / cm < ² >. In this test, when a predetermined switching voltage set in advance was reached, switching from charging to discharging was performed, and charging and discharging were performed for a plurality of cycles. After charge / discharge of each cycle, the cell resistivity (Ω · cm ² ) was determined for each sample. The cell resistivity is obtained by calculating an average voltage during charging and an average voltage during discharging in any one of a plurality of cycles, and {(difference between average voltage during charging and average voltage during discharging) / (average current / 2)} × The cell effective area was determined. In this example, the cell resistivity of the electrode immediately after the start of immersion in the electrolyte (0 days of immersion) was determined.

As a result, the cell resistivity was measured as Sample No. 1-1, 0.76 Ω · cm ² . 1-11 was 0.83 Ω · cm ² . Sample No. Compared to Sample No. 1-11, Sample No. The reason why the cell resistivity of 1-1 was reduced is that the catalyst part made of tungsten oxide is supported on the base made of carbon fiber, so that the catalytic function of the catalyst part is effectively exhibited, and the electrode This is thought to be due to the improved battery reactivity.

[Test Example 2]
As an electrode provided with a catalyst part containing a non-noble metal element, a simulated electrode in which the mass ratio occupied by the catalyst part in the electrode (existence ratio of the catalyst part) was changed was produced, and the cell reactivity in the catalyst part was examined.

[Sample preparation]
・ Sample No. 2-1 to 2-5
A simulated electrode including a conductive material and a catalyst portion held inside the conductive material was produced. To manufacture the simulated electrode, first, a cylindrical member made of plastic is prepared. Next, rod-shaped brass is inserted into the hollow portion on one end side of the cylindrical member, carbon paste oil (conductive material) is inserted into the hollow portion on the other end side, and the powder (tungsten oxide (WO ₃ ) powder). These powders are pressed to obtain a simulated electrode. In each sample, the abundance ratio between the carbon paste oil and the catalyst part (the above powder) was changed. Specifically, the abundance ratio of the catalyst portion is the sample No. 2-1, 0% by mass, sample no. In 2-2, 17% by mass, sample no. 2-3, 25% by mass, sample No. 2-4, 50% by mass, sample no. In 2-5, the content was 67% by mass. The abundance ratio of the catalyst part is a mass ratio of the content of the catalyst part when the total content of the carbon paste oil and the catalyst part (the above powder) is 100% by mass.

[Battery reactivity]
In the above sample No. Linear sweep voltammetry measurement was performed using electrodes 2-1 to 2-5. Specifically, the above sample No. Each of the electrodes 2-1 to 2-5 was immersed in a previously charged electrolytic solution, and potential scanning was performed. This electrolytic solution contains manganese ions having a concentration of 1.0 mol / L. The potential scan was performed at 3 mV / s from the open voltage (1.23 V) of the charged electrolyte to the low potential side using the silver / silver chloride electrode as a reference electrode. The result is shown in FIG. In FIG. 8, the horizontal axis represents the applied potential, and the vertical axis represents the response current value. In FIG. 2-1, thin solid line, sample no. 2-2 is a dotted line, Sample No. 2-3 is an alternate long and short dash line. 2-4 is a broken line, Sample No. 2-5 is indicated by a bold solid line.

In the linear sweep voltammogram shown in FIG. 8, the larger the peak potential, the faster the battery reaction rate on the electrode. Sample No. The peak potential of 2-1 is 1.04 V. The peak potential of 2-2 to 2-5 is around 1.20V. This potential of 1.20 V is considered to be a reduction potential of Mn ³⁺ → Mn ²⁺ in the electrolytic solution. Sample No. For 2-2 to 2-5, fee No. It can be seen that the peak potential is larger than that of 2-1. Sample No. The reason why the peak potential of 2-2 to 2-5 is large is considered to be that the catalytic function of the catalyst portion was effectively exhibited and the cell reactivity on the electrode was improved.

In the linear sweep voltammogram shown in FIG. 8, the larger the absolute value of the peak current value, the greater the battery reactivity on the electrode. Sample No. When comparing 2-2 to 2-5, it can be seen that a peak of the current value is observed near the potential of 1.2 V, and that the absolute value of the peak current value increases as the abundance ratio of tungsten increases. The reason why this tendency is observed is considered to be that the catalyst function of the catalyst part was more effectively exhibited as the presence ratio of the catalyst part was larger, and the cell reactivity on the electrode could be improved.

[Test Example 3]
As an electrode provided with a catalyst part containing a non-noble metal element, a simulated electrode in which the constituent elements of the catalyst part were changed was produced, and the cell reactivity in the catalyst part was examined.

[Sample preparation]
・ Sample No. 3-1 to 3-6, 3-11
Similar to Test Example 2, a simulated electrode including a conductive material and a catalyst portion held inside the conductive material was produced. In each sample, the constituent elements of the powder constituting the catalyst part were changed. Sample No. In 3-1, a powder of manganese oxide (MnO ₂ ) was used. Sample No. For 3-2, a powder of copper oxide (CuO ₂ ) was used. Sample No. For 3-3, cerium oxide (CeO ₂ ) powder was used. Sample No. For 3-4, powder of silicon oxide (SiO ₂ ) was used. Sample No. For No. 3-5, molybdenum oxide (MoO ₃ ) powder was used. Sample No. For 3-6, iron oxide (FeO) powder was used. Sample No. In all of 3-1 to 3-6, the abundance ratio of the catalyst part (the above powder) was 25 mass%. Sample No. 3-11 is composed only of carbon paste oil. That is, sample no. 3-11 is composed of 100% by mass of carbon paste oil, and the catalyst part (the above powder) is 0% by mass.

[Battery reactivity]
In the above sample No. Linear sweep voltammetry measurement was performed using simulated electrodes 3-1 to 3-6 and 3-11. The measurement conditions are the same as in Test Example 2. The results are shown in Table 1. Table 1 shows the peak voltage and the peak current at the peak voltage.

As shown in Table 1, sample no. Samples Nos. 3-1 to 3-6 are sample Nos. Compared to 3-11, the peak potential is large and the cell reaction rate is fast. In addition, fee No. Samples Nos. 3-1 to 3-6 are sample Nos. It can be seen that the absolute value of the peak current value is large and the battery reactivity is large compared to 3-11. The reason for this tendency is considered that the catalytic function of the catalyst portion was effectively exhibited and the cell reactivity on the electrode could be improved.

[Test Example 4]
An electrode having a catalyst part containing a non-noble metal element was produced, and the cell reactivity on the electrode was examined.

[Sample preparation]
・ Sample No. 4-1
An electrode including a substrate and a catalyst portion supported on the substrate was produced.
Using a carbon paper made of a plurality of carbon fibers as a substrate, a fiber assembly having a size of 3.3 mm × 2.7 mm and a thickness of 0.45 mm was produced. In this fiber assembly, the fiber diameter of each carbon fiber was 10 μm in terms of equivalent circle diameter, and the porosity was 85% by volume.
An aqueous solution containing manganese sulfate (MnSO ₄ ) was prepared as a coating solution containing the constituent elements of the catalyst part. The solvent (water) was 1% by mass with respect to the entire coating solution.
The said base | substrate was immersed in the said coating liquid, and the said coating liquid was made to adhere to the outer peripheral surface of a base | substrate (each carbon fiber). After drying the substrate to which the coating solution adhered, heat treatment was performed at 480 ° C. for 1 hour.

The obtained electrode (Sample No. 4-1) was examined for a cross section using a scanning electron microscope and an analyzer (SEM-EDX) using energy dispersive X-ray spectroscopy. As a result, sample no. In the electrode of 4-1, it was confirmed that the catalyst portion was present almost uniformly dispersed on the outer peripheral surface of the substrate (each carbon fiber). In addition, the crystal structure was measured by an X-ray diffraction method (XRD), and the element composition was measured by an X-ray microanalyzer (EPMA) to examine the existence state of the catalyst part. As a result, it was found that the catalyst portion exists in the form of manganese oxide (MnO ₃ ). The mass proportion of the catalyst portion in the electrode was 20%.

・ Sample No. 4-11
As an electrode, Sample No. A substrate similar to the substrate of 4-1 was produced. Sample No. The electrode 4-11 is composed only of the substrate and does not include a catalyst portion.

[Battery reactivity]
In the above sample No. 4-1 and Sample No. Linear sweep voltammetry measurement was performed using electrodes 4-11. The measurement conditions are the same as in Test Example 2. The results are shown in Table 2. Table 2 shows the peak voltage and the peak current at the peak voltage.

As shown in Table 2, sample No. 4-1, Sample No. It can be seen that the peak potential is larger and the battery reaction rate is faster than 4-11. Sample No. 4-1, Sample No. It can be seen that the absolute value of the peak current value is large and the battery reactivity is large compared to 4-11. The reason for this tendency is considered that the catalytic function of the catalyst portion was effectively exhibited and the cell reactivity on the electrode could be improved.

The present invention is not limited to these exemplifications, is shown by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. For example, the composition of the substrate and the catalyst part can be changed within a specific element and a specific range, or the type of the electrolytic solution can be changed.

1 Redox flow battery (RF battery)
DESCRIPTION OF SYMBOLS 100 Battery cell 11 Diaphragm 10 Electrode 110 Base body, 111 Catalyst part, 112 Binder 12 Positive electrode cell, 13 Negative electrode cell 14 Positive electrode, 15 Negative electrode 16 Cell frame 161 Bipolar plate, 162 Frame body 163,164 Supply manifold, 165,166 Drainage manifold 163s, 164s Supply slit, 165s, 166s Drain slit 167 Seal member 100P Positive electrode circulation mechanism, 100N Negative electrode circulation mechanism 18 Positive electrode electrolyte tank, 19 Negative

electrode electrolyte tank

20, 21, 22, 23 Conduit, 24, 25 Pump 200 Cell stack

200S Sub stack

210, 220 End plate, 230 Connecting member

Claims

A substrate and a catalyst portion supported on the substrate;
The substrate contains one or more elements selected from the group consisting of C, Ti, Sn, Ta, Ce, In, W, and Zn,
The catalyst portion contains one or more elements selected from the group consisting of Fe, Si, Mo, Ce, Mn, Cu, and W.
Redox flow battery electrode.
The redox flow battery electrode according to claim 1, wherein a mass ratio of the catalyst portion in the redox flow battery electrode is 0.01% or more and 70% or less.
The electrode for a redox flow battery according to claim 1 or 2, comprising the catalyst part having a part exposed from the base and a part embedded in the base.
The catalyst part is
A first catalyst portion having a portion exposed from the substrate;
The redox flow battery electrode according to any one of claims 1 to 3, further comprising a second catalyst portion embedded in the base body without being exposed from the base body.
The redox flow battery electrode according to any one of claims 1 to 4, further comprising a binder covering at least a part of the catalyst portion.
A redox flow battery for supplying and discharging a positive electrode electrolyte and a negative electrode electrolyte to a battery cell comprising a positive electrode, a negative electrode, and a diaphragm interposed between the positive electrode and the negative electrode. ,
The positive electrode is a redox flow battery electrode according to any one of claims 1 to 5,
Redox flow battery.
7. The redox flow battery according to claim 6, wherein the negative electrode is an electrode for a redox flow battery according to any one of claims 1 to 5.
The positive electrode electrolyte contains manganese ions as a positive electrode active material,
The redox flow battery according to claim 6 or 7, wherein the negative electrode electrolyte contains titanium ions as a negative electrode active material.
The redox flow battery according to claim 8, wherein the manganese ion concentration and the titanium ion concentration are 0.3 mol / L or more and 5 mol / L or less, respectively.